I'm not sure of the full contention of the article, but I guess you could mention things like:
->The first two pupils seated appear carefree and not in the least worried about what they've said - which almost indicates that they think they deserve to be there as they know that what they've done is wrong. Also, their slouched posture, and apathetic facial expressions make it appear as though they usually get sent to the principal for this sort of misbehaviour (i.e. it isn't their first time). In contrast, you have the third student who has an extremely worried and concerned facial expression, which shows that this may be his first time going to the principal's office. Thus, when his misdemeanour of saying the word "christmas" is indicated, we as readers feel even more outraged at these institutions for their misjudging of normally well-behaved children as being profane and unruly. The reader feels even greater sympathy towards the third boy and anger towards the overly politically correct institutions as the word "christmas" isn't even censored in the same way as the "S.H word" or the "F word". This shows that the institutions are unnecessarily condemning the use of a word which normally has innocent and celebratory connotations, rather than profane ones. Thus, the institutions appear to be deviated from the normal society, in what the reader perceives as not only an attack on the young boy, but on the celebration of Christmas as well.
->The principal is shown in the background as a shaded and hazy figure - this makes him seem more threatening and increases the sympathy we feel towards the students, particularly the third boy who said "Christmas" - and further accentuates how undeserving the boy is of such punishment and the foolishness of these institutions in being so overly and unnecessarily politically correct.